Mapping Mountains – Summit Relocations – 30-99m Twmpau and Y Trechol – The Dominant Hills of Wales

Park Quarry (SN 428 120)

There has been a Summit Relocation to a hill that is listed in the 30-99m Twmpau and Y Trechol – The Dominant Hills of Wales, with the summit and bwlch height and position confirmed by LIDAR analysis conducted by Myrddyn Phillips.

LIDAR image of Park Quarry

The criteria for the two listings that this summit relocation applies to are:

30-99m Twmpau - Welsh hills at or above 30m and below 100m in height with 30m minimum drop, with an accompanying sub list entitled the 30-99m Sub-Twmpau with the criteria for this sub category being all Welsh hills at or above 30m and below 100m in height with 20m or more and below 30m of drop, with the word Twmpau being an acronym standing for thirty welsh metre prominences and upward.

Y Trechol - The Dominant Hills of Wales - Welsh P30 hills whose prominence  equal or exceed half that of their absolute height.  With the criteria for Lesser Dominant status being those addition Welsh P30 hills whose prominence is 33.3% or more and below 50% of their absolute height, with the Introduction to the Mapping Mountains publication of this list appearing on the 3^rd December 2015.

The name of the bounded land where the summit of the hill is situated is Park Quarry and this was derived from the Tithe map, and it is adjoined to the Mynydd Sylen group of hills, which are situated in the western part of South Wales (Region C, Sub-Region C1), and is positioned with the stream valley of the Gwendraeth Fach to the south and east, and the A 484 road to the west, and has the small town of Cydweli (Kidwelly) towards the south.

As this hill is not a part of designated open access land permission to visit should be sought, for those wishing to do so the most convenient approach is from the farm of Ystrad-fawr which is to the west south-west of the summit.

Prior to LIDAR analysis this hill was listed with c 47m of drop based on the 93m summit spot height that appears on the Ordnance Survey 1:25,000 Explorer map and an estimated bwlch height of c 46m based on interpolation of bwlch contouring between 45m – 50m. 

Extract from the Ordnance Survey Interactive Coverage Map hosted on the Geograph website showing one of the two equal heighted LIDAR summit positions in relation to the position of the spot height

The position of the 93m spot height appears at a field boundary that comprises a raised hedge which is considered to be a relatively recent man-made construct, therefore if a natural summit exists for this hill, even if lower than the hedge bank, the listed summit would be given to this position.

1m DTM LIDAR analysis gives the following:

Raised hedge bank:  93.999m at SN 42874 12092

Natural summit:  93.919m at SN 42853 12091 and SN 42859 12091

LIDAR image for Park Quarry showing the natural summit left of centre and the high point of the raised hedge bank in the centre of the image

Therefore, the height produced by 1m DTM LIDAR analysis for the natural summit of this hill is 93.9m and is positioned at SN 42853 12091 and SN 42859 12091.  These positions are not given a spot height on Ordnance Survey maps and are 21 metres and 15 metres respectively, west from where the high point of the raised hedge bank is positioned and approximately 30 metres from where the 93m spot height appears on the ground.

The full details for the hill are:

Group:  Mynydd Sylen

Name:  Park Quarry

Summit Height:  93.9m (LIDAR)

OS 1:50,000 map:  159

Summit Grid Reference (New Position):  SN 42853 12091 and SN 42859 12091 (LIDAR)  

Drop:  48.5m (LIDAR)

Dominance:  51.63% (LIDAR) 

Myrddyn Phillips (November 2018)